(1) Field of the Invention
The present invention relates to a controller, and more particularly relates to a controller for protectively reducing an output of a converting circuit.
(2) Description of the Prior Art
The conventional power management Integrated Circuits (ICs) immediately stop operating and execute a latching protection for avoiding damage to the integrated circuits and systems and further ensuring the safety and reliability of integrated circuits when judging that the system operates abnormally to trigger a corresponding protection mechanism, such as over-temperature protection, over-voltage protection, under-voltage protection, over-current protection and so on.
FIG. 1 is a schematic diagram of a conventional DC-DC buck converter. The DC-DC buck converter comprises a controller and a converting circuit. The controller comprises a feedback circuit 10, an over-voltage judgment circuit 15, a logic control circuit 20 and a latch protection circuit 25. The converting circuit comprises a high-side transistor switch SW1, a low-side transistor switch SW2, an inductance L and an output capacitance C. The high-side transistor switch SW1 and the low-side transistor switch SW2 are connected in series. One end of the high-side transistor switch SW1 is coupled to an input voltage Vin, and the other end thereof is coupled to one terminal of the inductance L and one end of the low-side transistor switch SW2. The other end of the low-side transistor switch SW2 is grounded. The other terminal of the inductance L is coupled to the output capacitance C for providing an output voltage Vout. An output voltage detecting circuit VD is coupled to the converting circuit and generates a feedback signal VFB according to the output voltage Vout. The feedback circuit 10 generates a modulation signal Sp according to the feedback signal VFB and a reference signal Vr. The logic control circuit 20 generates control signals S1 and S2 according to the modulation signal Sp to respectively turn on/off the high-side transistor switch SW1 and the low-side transistor switch SW2. The over-voltage judgment circuit 15 receives the feedback signal VFB and an over-voltage reference signal Vov, and generates a high level signal when a level of the feedback signal VFB is higher than a level of the over-voltage reference signal Vov. At the moment, the latch protection circuit 25 immediately generates a latch signal LS when receiving the high level signal generated by the over-voltage judgment circuit 15 until the controller is restarted. The logic control circuit 20 stops generating the control signals S1 and S2 when receiving the latch signal LS, and turns off the high-side transistor switch SW1 and the low-side transistor switch SW2 of the converting circuit.
However, the controller immediately stops operation in some specific application environment, such as a remote control airplane, which would result in that the remote control airplane is out of control. The remote control airplane may crash if the controller cannot recover the power supplying system in a short time.